It is something else, see attachment, image of a working addin but it's not visible in the version control addin selection.

Would like to know the purpose of that. Looking for a way to integrate name changes.
Now if you change the name of a block the link still contains the old name.

Not sure how you got the configure workspace menu to open.

You clearly imported the addin the right way from my pov.

Instead of 

public class AddIn : ContextMenuAddIn

You have to use:

public class AddIn : VciRepositoryAddIn

This makes it visible in the workspace configuration
protected override void BuildContextMenuItems(ContextMenuAddInRoot addInRootSubmenu) does not work anymore then.

Another discovery after a lot of digging:
You can get the information about Vci like this:
_tiaPortal.Projects.First().GetService<VersionControlInterface>()

https://support.industry.siemens.com/cs/ww/en/view/109773999 

There is an Add in now

Hello all,

the same problem is at TIA V16.

I copy the Siemens.VCIGitConnector.addin in the Add-ins Folder but then I can not select that add-ins.

After update TIA  to Version V16 Update 1 then it work.

You can use the normal git commands by the pull down menu (add, commit).

If you want use push, pull then you have to configure the git server by the git-bash.

Have a good time

Günter